I’ve just always assumed that big stores were collecting and selling every iota of data they could.

I recall reading about retailers using license plate scanning in their parking lots in the early aughts.

I recall reading about retailers using license plate scanning in their parking lots in the early aughts.

They also pick up the unique IDs from the wireless air pressure monitor chips in your tires.

Even if you don't have an internet-connected car, they're still tracking you from parking lot to parking lot. That information can then be combined with time/date information and your credit/debit card purchase to identify who you are, where you shop, and what you buy.

Yep, that technology is called ANPR - automatic number plate recognition. Outputs a license plate, state, date/time, and gps coord of scanner.

> They also pick up the unique IDs from the wireless air pressure monitor chips in your tires.

That's called TPMS, tire pressure monitoring system. There is 1 device per tire, which emits temp, pressure, serial#, and other data. You can decode this for yourself with https://github.com/merbanan/rtl_433 and a RTL-SDR.